The present invention relates generally to security systems. More particularly, this invention relates to a vehicle security apparatus and method for enabling a motor vehicle to be started or for starting a motor vehicle, both of which prevent unauthorized use and theft of an automobile or motor vehicle.
On an economical level, vehicle theft causes the yearly loss of millions of dollars in the United States. The severity of economic loss from vehicle theft continues to increase, particularly in the case where the value of a vehicle is worth more as individual parts than as a complete operating vehicle. On an emotional level, vehicle theft causes anguish and suffering to a vehicle owner upon discovery that his or her parked vehicle along with other important and valuable items contained inside have been stolen.
Vehicle manufacturers generally install conventional tumbler locks operable by keys for use on doors, trunks, and ignition switches for preventing unauthorized use and combating vehicle theft. Similar tumbler locks are typically used to protect access to the ignition system of such vehicles. A problem particularly associated with a conventional ignition switch used to start the motor vehicle is that the ignition switch is electrically connected in series between two separate electrical circuits required for starting the vehicle's motor. Specifically, in such an arrangement a first electrical circuit connects the ignition switch electrically in series between the vehicle's 12 volt battery and the vehicle's coil. A second electrical circuit connects the ignition switch electrically in series between the vehicle's battery and the vehicle's starter solenoid. In operation, when the ignition switch is in the "OFF" position both electrical circuits are open and the motor is not operable. By rotating a key in the ignition switch to the "ON" position, the first electrical circuit is closed and current flows from the battery to the coil for supply of electrical power to the vehicle's distributor and spark plugs. By momentarily further rotating the key in the ignition switch to the "START" position the second electrical circuit is momentarily closed and current flows from the battery to the starter solenoid to activate the vehicle's starter motor and start the motor. Use of such a conventional series-connected ignition switch permits even an inept thief to easily and quickly start the motor vehicle without a key by circumventing the ignition switch to connect the electrical circuits. In other words, a thief can easily, "hot-wire" a vehicle to by-pass such a conventional ignition switch to start the motor vehicle.
Some anti-theft systems for vehicles modify a conventional ignition switch of tumbler locks operable by keys to prevent unauthorized use of a motor vehicle and to combat vehicle theft by a thief "hot wiring" the electrical circuits to start the motor vehicle. For example, one vehicle manufacturer installs in its upper end model lines a Vehicle Anti-Theft (VAT) System that includes an ignition pass key, a modified conventional ignition switch, a decoder module and a starter enable relay electrically connected in series between the ignition switch and the vehicle's starter solenoid. Specifically, the VAT system modified ignition switch has contacts for engaging a single electrical resistor pellet embedded in the upper shaft of the key. The single resistance value of the pellet is compared against a resistance value stored in the decoder module that is remotely located from the ignition switch. If the resistance value of the pellet is correct, the decoder module grounds the starter enable relay that enables current to flow to the starter solenoid when the key in the ignition switch is momentarily rotated to the "START" position.
Another example of a modified conventional ignition switch is described in U.S. Pat. No. 5,132,661 granted to Pinnow, which discloses a security system that includes a modified conventional ignition switch having an optical key shape reader to photo-electrically derive a single electric signal from shape characteristics of a key widen the key is inserted in the ignition switch. The shape characteristics of the key consist of the standard contoured shape of a key, or a pattern of slots or holes which are introduced into the upper or lower shaft of the key. The signal is transmitted through wires to a decoder at a remote location where the signal is processed to determine whether it corresponds to a valid key shape. If the signal corresponds to a valid key shape, the decoder issues an enable signal to a relay to enable an appropriate function, thereby, enabling the vehicle's starter or its fuel injector.
A problem with the above systems is the limitation to only a single signal out of a few possibilities. In one embodiment of the VAT system the value of resistance is limited to one of 15 different resistance values ranging from 380 ohms to 12,300 ohms. In Pinnow, the system is limited to shape characteristics which produce a discernible signal, such as well-defined key cuts, or 3 to 4 slots or holes introduced in the upper or lower shaft portion of the key.
Another problem associated with the VAT system is that the resister pellet is likely to fall out, become dirty, or receive improper electrical contact, all of which will lead to improper identification. Another problem associated with the system disclosed by Pinnow, is that the signal is not constant but varies each time the vehicle owner inserts the key into the ignition switch to generate a signal. Specifically, insertion of the key activates a light emitting diode and decoder for processing the shape characteristics of the key in which the generated signal is dependent on the speed with which the vehicle owner inserts the key. The varying signal thus generated lead to an increased likelihood that use of an authorized key will produce a signal that is misinterpreted by the decoder as an unauthorized use. Misinterpretation by the decoder is particularly troublesome since both systems incorporate delay modes which require a vehicle owner to wait several minutes before retrying to start the motor vehicle.
Other anti-theft systems work in combination with conventional mechanisms of tumbler locks operable by keys to prevent or deter a thief by increasing the difficulty and time associated in stealing a vehicle. For example, U.S. Pat. No. 5,119,065, granted to Wiehagen, discloses a lock body having two discrete electromagnetic radiation emitters connected by optical fibers to the side of the lock body so that electromagnetic radiation traverses a key receiving slot. Insertion of a key into the slot containing the proper predetermined corresponding areas, one for reflection of the radiation and an other for absorption of the radiation, activates a desired operation in the motor vehicle. The optical fibers are used solely for transmission or retransmission of the same radiation from the emitters.
Still other anti-theft systems replace the conventional mechanisms of tumbler locks operable by keys. For example, U.S. Pat. No. 4,742,327 granted to Burgess et al., discloses a device to prevent access to the interior of a vehicle by use of a keyless access and security system that includes a piezoelectric permutation touch pad unit. A person seeking access must enter the correct access code combination on the touch pad to open the door or trunk. Upon entering an improper access code an alarm system is activated. A drawback of this system is the time-consuming effort required by the vehicle owner to properly enter the correct sequence of various numbers each time upon entering a locked motor vehicle.
For completeness, U.S. Pat. No. 5,159,334 granted to Baumert et al., discloses a remote-control system for locks. The disclosed system includes an infrared hand-held transmitter that is used for remote control of the central locking system of a motor vehicle. In addition, the transmitter can be received in a receptacle from which the transmitter can transmit a signal through a optical fiber to a plurality of exit holes on the vehicle body outer skin for transmission of the signal to an external garage door driver. Baumert et al. neither teaches the use of a transmitter as a vehicle security apparatus for enabling the motor vehicle to be started nor as a vehicle security apparatus for starting the motor vehicle, and instead teaches away from the invention herein described by directing a signal initially within the vehicle out and away from the vehicle.